基於JDBC進行資料庫的增刪改查
阿新 • • 發佈：2020-11-27
package com.neusoft.dao.impl; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.util.ArrayList; import java.util.List; import com.neusoft.dao.EmpDao; import com.neusoft.po.Emp; import com.neusoft.util.CommonUtil; import com.neusoft.util.DBUtil; public class EmpDaoImpl implements EmpDao {// 實現類 private Connection con = null; private PreparedStatement pst = null; private ResultSet rs = null; // 全查詢 @Override public List<Emp> selectEmpAll() { List<Emp> list = new ArrayList<>();// 查詢多行,所以準備容器 String sql = "select * from emp order by empno"; try { con = DBUtil.getConnection(); pst = con.prepareStatement(sql); rs = pst.executeQuery(); while (rs.next()) { Emp emp = new Emp(); emp.setEmpno(rs.getInt("empno")); emp.setEname(rs.getString("ename")); emp.setJob(rs.getString("job")); emp.setHireDate(rs.getString("hiredate")); emp.setSal(rs.getDouble("sal")); emp.setDeptno(rs.getInt("deptno")); list.add(emp); } } catch (Exception e) { e.printStackTrace(); } finally { DBUtil.closeAll(rs, pst, con); } return list; } // 根據ID查詢,返回受影響的 public Emp selectEmpById(int empno) { Emp emp = null; String sql = "select * from emp where empno=?"; try { con = DBUtil.getConnection(); pst = con.prepareStatement(sql); pst.setInt(1, empno); rs = pst.executeQuery(); if (rs.next()) { emp = new Emp(); emp.setEmpno(rs.getInt("empno")); emp.setEname(rs.getString("ename")); emp.setJob(rs.getString("job")); emp.setHireDate(rs.getString("hiredate")); emp.setSal(rs.getDouble("sal")); emp.setDeptno(rs.getInt("deptno")); } } catch (Exception e) { e.printStackTrace(); } finally { DBUtil.closeAll(rs, pst, con); } return emp; } // 新增,返回受影響的行數 public int insertEmp(Emp emp) { int result = 0; String sql = "insert into emp values(null,?,?,?,?,?)"; try { con = DBUtil.getConnection(); pst = con.prepareStatement(sql); pst.setString(1, emp.getEname()); pst.setString(2, emp.getJob()); pst.setString(3, CommonUtil.getCurDate());// 獲取系統日期 pst.setDouble(4, emp.getSal()); pst.setInt(5, emp.getDeptno()); result = pst.executeUpdate(); } catch (Exception e) { e.printStackTrace(); } finally { DBUtil.closeAll(null, pst, con); } return result; } // 更新工資和職位 public int updateEmp(Emp emp) { int result = 0; String sql = "update emp set job=?,sal=? where empno=?"; try { con = DBUtil.getConnection(); pst = con.prepareStatement(sql); pst.setString(1, emp.getJob()); pst.setDouble(2, emp.getSal()); pst.setInt(3, emp.getEmpno()); result = pst.executeUpdate(); } catch (Exception e) { e.printStackTrace(); } finally { DBUtil.closeAll(rs, pst, con); } return result; } // 刪除 public int deleteEmpById(int empno) { int result = 0; String sql = "delete from emp where empno=?"; try { con = DBUtil.getConnection(); pst = con.prepareStatement(sql); pst.setInt(1, empno); result = pst.executeUpdate(); } catch (Exception e) { e.printStackTrace(); } finally { DBUtil.closeAll(rs, pst, con); } return result; } }
package com.neusoft.dao; import java.util.List; import com.neusoft.po.Emp; public interface EmpDao { public List<Emp> selectEmpAll();//全查詢 public Emp selectEmpById(int empno);//根據主鍵查詢 public int insertEmp(Emp emp);//新增 public int updateEmp(Emp emp);//修改 public int deleteEmpById(int empno);//刪除 }
package com.neusoft.po; public class Emp {// 實體類,和資料庫資料一一對應 private Integer empno; private String ename; private String job; private String hireDate; private Double sal; private Integer deptno; @Override public String toString() { return this.empno + "\t" + this.ename + "\t" + this.job + "\t" + this.hireDate + "\t" + this.sal + "\t" + this.deptno; } public Integer getEmpno() { return empno; } public void setEmpno(Integer empno) { this.empno = empno; } public String getEname() { return ename; } public void setEname(String ename) { this.ename = ename; } public String getJob() { return job; } public void setJob(String job) { this.job = job; } public String getHireDate() { return hireDate; } public void setHireDate(String hireDate) { this.hireDate = hireDate; } public Double getSal() { return sal; } public void setSal(Double sal) { this.sal = sal; } public Integer getDeptno() { return deptno; } public void setDeptno(Integer deptno) { this.deptno = deptno; } }
package com.neusoft.util;
import java.text.SimpleDateFormat;
import java.util.Date;
public class CommonUtil {// 共通的非JDBC的工具類類
// 獲取系統日期
public static String getCurDate() {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
return sdf.format(new Date());
}
}
package com.neusoft.util;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
public class DBUtil {
private static final String URL = "jdbc:mysql://localhost:3306/emp?characterEncoding=utf-8";
private static final String DRIVER = "com.mysql.jdbc.Driver";
private static final String USERNAME = "root";
private static final String PASSWORD = "root";
// 獲取Connection連線
public static Connection getConnection() {
Connection con = null;
try {
Class.forName(DRIVER);
con = DriverManager.getConnection(URL, USERNAME, PASSWORD);
} catch (Exception e) {
e.printStackTrace();
}
return con;
}
// 關閉資源
public static void closeAll(ResultSet rs, PreparedStatement pst, Connection con) {
try {
if (rs != null) {
rs.close();
}
if (pst != null) {
pst.close();
}
if (con != null) {
con.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
}
}
package com.neusoft;
import java.util.List;
import com.neusoft.dao.EmpDao;
import com.neusoft.dao.impl.EmpDaoImpl;
import com.neusoft.po.Emp;
public class Test {
public static void main(String[] args) {
EmpDao dao = new EmpDaoImpl();
//全查詢
/*
List<Emp> list = dao.selectEmpAll();
if(list.size()==0){
System.out.println("沒有資料");
}
for(Emp emp : list){
System.out.println(emp);
}
*/
/*
//根據主鍵查詢
Emp emp = dao.selectEmpById(10);
if(emp!=null){
System.out.println(emp);
}else{
System.out.println("查無此人");
}
*/
/*
Emp emp = new Emp();
emp.setEname("習大大");
emp.setJob("國家主席");
emp.setSal(9000.32);
emp.setDeptno(10);
int result = dao.insertEmp(emp);
if(result>0){
System.out.println("新增成功");
}else{
System.out.println("新增失敗");
}
*/
/*
Emp emp = new Emp();
emp.setEmpno(75);
emp.setJob("國家主席1");
emp.setSal(9000.33);
int result = dao.updateEmp(emp);
if(result>0){
System.out.println("更新成功");
}else{
System.out.println("更新失敗");
}
*/
int result = dao.deleteEmpById(75);
if(result>0){
System.out.println("刪除成功");
}else{
System.out.println("刪除失敗");
}
}
}
